The present invention relates to mining vehicles and, more particularly, to a battery powered mining shuttle car.
One function that always must be performed during mining is to transport mined material from the point of mining to a point of discharge, such as into a feeder device which ultimately transports the mined material to the mine mouth. Starting at least as early as the 1940's (e.g., see U.S. Pat. Nos. 2,192,650; 2,588,341 and 3,370,667), this was accomplished utilizing a battery powered vehicle with a central conveyor. In order to maximize production level and equipment utilization, it was customary to use two or more shuttle cars that were loaded and discharged alternatively. The flexibility of the movement of the shuttle car is important as it requires travel through the labyrinth maze of a mine. In commercial embodiments, shuttle cars were powered by a 300 amp hour storage battery mounted at one end of the shuttle car. It soon became apparent, however, that a battery, the size and capacity of which had been dictated by the constraints of the vehicle configuration, mining dimensions, and other technology of the time, coupled with the realities of weight and balance, was an impractical energy source in production mining environment.
As a result, from the mid-1940'to today, the majority of commercial shuttle cars have been powered by trailing cables through vehicle-mounted cable reels. As a consequence, however, a shuttle car can no longer travel independently in the shortest possible distance between the production face and the dump point. Also, no longer can more than one car travel the same route without interference from other cars, and no longer can the mining supervisor extend the haulage to meet other needs without additional complications, such as the splicing-in of additional cable which cannot be accommodated on the cable reel.
In order to overcome the limitations of cable reel shuttle cars, several manufacturers have developed and market battery powered haulage vehicles of another type to compete for the haulage market. These vehicles are designed with the battery on one end and a haulage compartment on the other end, with the operator's compartment situated in between. The vehicle is articulated in order to be able to maneuver in a mining environment.
While such a design is optimal for the incorporation of large 1500 amp hour or greater batteries, there are a number of operational disadvantages for such a vehicle. The haulage compartment does not have the through-the-vehicle conveyor of the shuttle car, and as a result, the vehicle must be loaded while facing in one direction, and the hauled material must be discharged in the opposite direction, thereby necessitating vehicle reversal at least once in each direction of travel.
In addition to the extra cycle time required for this maneuver, the additional electrical energy required to travel the extra distance involved, plus the additional electrical energy required to stop, start, and steer the shuttle car during reversal, all subtract from the finite amount of energy available on the on-board storage battery.
The articulated configuration of this type of car also makes it difficult to provide all-wheel drive. Two wheel drive produces traction problems in the wet, soft bottoms and gradients that characterize many mining operations. Some exemplary embodiments of the articulated vehicles can be optionally equipped at a considerable extra price with manually-actuated, hydraulic drive for the other wheels, an arrangement that also consumes electrical energy at a very high rate when placed in operation. Often this manual-actuation tales place after the vehicle is immobilized and in a state that would not have occurred if the vehicle had been equipped with full-time, all-wheel drive. The traction problem is further exacerbated by the uneven distribution of weight carried by the tires, especially when the shuttle car is traveling in the unloaded portion of the cycle.
The consistently high loading of the tires on the battery/traction end of the shuttle car also shortens the life of these tires, so much so that some manufacturers have even resorted to solid tires constructed of synthetic, non-rubber materials with attendant reductions in tractive capabilities as an undesirable trade-off.
Additionally, in the use of shuttle cars, it is typical that there is an elevating discharge assembly (which can be raised and lowered) at the discharge (unloading) end, particularly for cable shuttle cars. For many purposes, however, such an elevating structure is not useful, and with the particular battery powered shuttle car of this invention, it can be much more desirable to provide a fixed height discharge at the unloading end.
When operating shuttle cars, it is highly desirable that the operator be able to effectively determine the proper position of the load with respect to the discharge end in order to avoid spillage on the floor. It is difficult to position the operator's compartment safely and effectively (so that the operator can easily operate the shuttle car), while not interfering with the coal or other mined material transport function of the conveyor, and still allow the operator to see when the shuttle car is “full” of material, so that it should be operated to go to a discharge location. To solve this problem, it may be desirable to incorporate a load indicator or the like viewable to the operator.
Also, it is necessary that the batteries that are provided with the shuttle car be able to be safely utilized in a mine environment. In particular, it is desirable to be able to de-energize the battery box either in a non-operating condition of the shuttle car, or in response to a particular condition.